The present invention relates to an apparatus for forming plastic preforms into plastic containers and a blow mould carrier. Such devices has been known for some time in the prior art. Normally, plastic preforms are formed into plastic containers by pressurization with compressed air in a plurality of blowing stations. As part of the expansion process, a number of successive movement processes take place. Normally the blow mould carrier halves are pivoted apart for insertion of a plastic preform and then pivoted together in order to perform the expansion process. After the end of the expansion process, the blow mould carrier parts are pivoted apart again to be able to remove the finished blown plastic container. When the blow mould carrier parts are in the closed state, in particular during the expansion process, in addition the blow mould carrier parts are locked together in order to be able to withstand the not inconsiderable pressures. Normally a pressure pad mechanism is arranged on one of the two blow mould carrier parts in order, for the duration of the prevailing interior pressure in the blowing process, to press the two blow moulds arranged on the blow mould carrier parts together with greater force than that provoked by the blowing pressure. Thus visible joint seams on the containers produced are kept as small as possible.
Furthermore sterile applications are known from the prior art in which the individual blowing stations are conducted inside a clean room. For example WO 2010/020529 A2 describes an apparatus for forming plastic preforms into plastic containers, which has a transport device comprising several blowing stations and a clean room.
By means of the clean room, aseptic conditions can be guaranteed in the production of the plastic containers and also during their filling with drinks.
The subject of WO 2010/020529-A2 is hereby made fully the subject of the present disclosure by reference.
As stated above, an important component of a blowing station is the locking mechanism which connects or locks the two mould carrier halves together during the blowing process. After the end of the blowing process, the lock opens. After opening the mould, the bottle can be removed and a new preform inserted. In the prior art, these locking mechanisms normally have a locking shaft mounted in one of the two mould carriers. Several bearing points distributed over the height of the mould carrier guarantee an even force distribution in the components. This is important since the lock must withstand a holding force of several 10,000 N. The locking process consists for example of a rotary or linear movement of the lock. This movement is normally generated by a stationary curve attached to the base structure of the machine, and transferred to the locking shaft via various deflections.
The opening and closing movement of the mould carrier is independent of this and controlled separately. Control takes place via a stationary control curve. For complete control therefore two curves are required, one to control the two mould carrier halves and one to control the lock.
It may also be necessary to provide a tempering of the blow moulds and/or the blow mould carrier shells in order to cool or heat the plastic surface quickly on expansion.
It has been found that the two blow mould carrier parts are subject to different requirements.
For example it is possible that asymmetric opening of the blow mould carrier parts offers kinematic advantages, in order to be able to insert the preforms in the blow mould gently (for the preform and control curves of the blow mould and the transfer stars for insertion and removal). If for this, one blow mould carrier part must be pivoted further than the other, the forces on the one are higher.
Furthermore a blow mould carrier part must resist the above-mentioned pressure pad mechanism, which again makes this heavier.
Furthermore it is possible to pivot the above-mentioned locking mechanism with the blow mould carrier parts. This locking mechanism normally has moving parts (e.g. a rotatable hook) which must be held by at least one blow mould carrier part, which again makes this heavier, while the other blow mould carrier part need merely provide a surface to create a form fit for the moving parts of the other (e.g. a groove to receive the hook).
It is therefore desirable to adapt the blow mould carrier parts of a blowing station to the different requirements, in particular with regard to the kinematics and weight.